The present invention relates generally to systems which use and generate images during medical and surgical procedures, which images assist in executing the procedures and indicate the relative position of various body parts and instruments. In particular the invention relates to a system for generating images during medical and surgical procedures that indicate a change in the condition or configuration of a medical instrument being used, wherein the system provides a positive indication of the position of a removable or interchangeable portion of the instrument.
A number of different types of surgical navigation systems have been described that include indications of the positions of medical instruments used in medical or surgical procedures. For example, U.S. Pat. No. 5,383,454 to Bucholz; PCT Application No. PCT/US94/04530 (Publication No. WO 94/24933) to Bucholz; and PCT Application No. PCT/US95/12894 (Publication No. WO 96/11624) to Bucholz et al., the entire disclosures of which are incorporated herein by reference, disclose systems for use during a medical or surgical procedure using scans generated by a scanner prior to the procedure. Surgical navigation systems typically include tracking means such as for example an LED array on the body part, emitters on the medical instruments, a digitizer to track the positions of the body part and the instruments, and a display for the position of an instrument used in a medical procedure relative to a body part. Although these types of systems are effective, further improvements are now possible for tracking the change of instrument configuration during surgery. For example, when using a high speed drill or other tool in surgery, typically this instrument uses an interchangeable attachment that allows for the use of different tool tips, such as for example different length drill bits and burrs. A simple, reliable way is desirable for the change in these tips to be indicated by the surgical navigation system to require the user or surgeon to properly recalibrate or reregister the position of the end of the instrument tip relative to some known point.
Additionally, if the emitter on an attachment end is not stably positioned, the navigation system may lose information on the location of the attachment and tool tip. The advantage of a stable geometry is that the position of the working portion of the instrument with respect to the LED array cannot be changed by the user. In prior art systems the LED array is generally attached to the surgical drill. If the user changes the attachment or the attachment is unscrewed slightly from the drill then location information may be lost. One example of this is an angled attachment that is screwed onto an image guided drill. The tip of this attachment can describe an arc as it is unscrewed from the drill because the LED array is not co-axial with the working portion of the attachment and location information may be lost; however, if the LED array is more permanently connected, as with the present invention, for example such as to a tool attachment, then the relationship between the LED array and working portion of the instrument is generally constant regardless of whether the attachment is loosened or not.
Other attachments to an instrument, such as for example a bent end craniotome, may favor a rotatable connection of an emitter to the attachment to allow the user to point the tip of an attachment (which may be at an angle to the instrument shaft) in the desired direction and still have a continued line of sight emission to the digitizer camera while rotating the attachment relative to the navigation system. Given the above information, it is sometimes advantageous for a surgeon to be able to rotate a surgical drill attachment in order to position the attachment in a specific way. For example, a portion of a surgical burr may be covered by a cowl (connected to the attachment) so that the burr can cut in only one direction. In order to position the cutting portion of the burr, the surgeon may have to rotate the attachment, and the LED array may be forced to point away from the digitizer camera when the attachment is rotated. However, if the attachment and LED array are connected so that they can rotate independently, as in for example, an alternative embodiment of the invention described herein, then the LED array can be directed toward the camera and the attachment still rotated in the desired direction. This concept is feasible in situations where the LED array and working portion of the attachment are coaxial (e.g. xe2x80x9cstraight attachmentsxe2x80x9d).
In light of the foregoing, there is a need in the art for an improved surgical navigation system and method for indicating a change in instrument configuration that provides a means to reliably calibrate the location of an instrument with interchangeable tips that does not significantly affect the accuracy of the localization of the system.
Accordingly, the present invention is directed to a medical instrument with a tracking means able to locate the position of the instrument in a surgical field, such as electrically energizeable emitters, reflective markers, magnetic sensors or other locating means, for use with a surgical navigation system and method that substantially improves the task of positively indicating to the surgical navigation system when an instrument attachment has been changed or removed and positively providing a link between the position of this changeable instrument attachment and the image provided by the surgical navigation system.
To achieve these objects and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention in one embodiment is an apparatus for use with a surgical navigation system and comprises a tool body, an instrument attachment onto which a tracking means such as, for example, emitters are fixedly mounted, at least one tool tip for removably coupling with the instrument attachment, a sensor positioned to be automatically operated when the tool tip is changed either by coupling the tip to or removing the tip from the instrument attachment, a controller responsive to the operation of the switch to detect when the tip has been changed, and an alarm responsive to the controller for indicating that the tool tip has been removed or changed so that the tip can be relocated relative to a known position in the surgical navigation system.
In another aspect, the sensor operated when the tool tip is changed is an electrical switch, such as for example a microswitch.
In another aspect, the surgical navigation system disables the tool when the electrical switch has been operated until the tool tip position is calibrated relative to a known position in the surgical navigation system. In this manner, the navigation system indicates the accurate tool tip location during the operation of the tool.
In another aspect, the electrical switch operates in response to the insertion or release of a tool tip to an attachment or to the tool body such as, for example, by pressing an attachment ring against the switch and a mechanical release, such as for example a chuck, to simultaneously activate the switch when releasing or attaching a tool tip. In this manner, the navigation system need not rely on the operator to know or remember to indicate a change in tool tips. The instrument automatically indicates this change or removal in tool tip to allow the navigation system to properly respond.
In another aspect, the surgical navigation system communicates to the user, for example, by means of a flashing LED on the tool tip instrument attachment or tool body, to positively indicate the attachment and relocation of the tool tip. In this manner, the user knows, by positive indication back from the navigation system, that it can proceed.
In another aspect, emitters are fixedly attached to the instrument attachment. This is accomplished, for example, by press fitting a cage that holds the emitters in place onto the instrument attachment. By fixedly attaching the emitter to the instrument attachment, the user or operator reduces the risk that loss in positioning will occur during the procedure due to an emitter erroneously changing its location relative to the instrument attachment or tool tip.
In another aspect, an emitter is rotatably connected to the instrument attachment. This is accomplished, for example, by providing a groove inside the end of a cage at the position where the tool attachment connects to the cage and disposing bearings or other rotatable devices in the groove to facilitate free rotation of the tool attachment and tool tip. By rotatably connecting the instrument attachment to the cage, the operator can more readily achieve a line of sight indication from the emitter, fixed to the cage, back to the digitizer of the navigation system which is less dependent on the orientation of the instrument attachment and tool tip.
In another aspect, the emitters attached to the tool are light emitting diodes (xe2x80x9cLEDsxe2x80x9d).
In another aspect, the controller is a suitably programmed personal computer (xe2x80x9cPCxe2x80x9d) or appropriate computer device.
In another aspect, the alarm is a visual designation or indicator on a PC monitor display or audible indication.
In another aspect, calibration of the tool tip location is accomplished by the user returning the tool tip to a datum, benchmark or known position for calibrating the location of the tip in three dimensional space. This simple method of calibration avoids the necessity of reentering data corresponding to a change in tool tips to accurately locate the tool tip.
In another aspect, calibration is accomplished, for example, by fiber optic reading of a bar code on the tool tip. In this manner, the operator is further allowed easy entry of the accurate calibration and configuration of the tool tip without the need for data entry.
In another aspect, calibration is accomplished by selection of options from a menu displayed by the navigation system. This aspect of the apparatus and method provides further simple and easy access to enter an accurate configuration and location without complicated data entry.
In addition, the invention in one embodiment comprises a surgical navigation system including: a controller; a tool and tool tip; a means for coupling a tool tip; a means for detecting the coupling and uncoupling of the tool tip; a means for delivering an alarm when the tool tip is changed by uncoupling or coupling; and a means for recalibrating or relocating the tool tip relative to a known point in the surgical navigation system.
In addition, the invention further comprises a method for monitoring the location of an instrument, an instrument attachment, and tool tip used in a surgical navigation system comprising the steps of: coupling an instrument attachment having at least one emitter to a tool; automatically tripping a switch in response to the coupling step occurring; delivering an alarm when the tool tip is coupled and uncoupled; and calibrating the tool tip relative to a known position in the surgical navigation system.
The objects of the invention are to provide a user, such as a surgeon, with the system and method to track an instrument used in conjunction with a surgical navigation system in such a manner that changing the tool tip or attachment of the instrument does not substantially affect the accuracy of the localization of the system.
It is a further object of this invention to provide a system and method to simply and yet positively indicate to the user a change in configuration, such as the removal or change of an instrument attachment or tool tip (e.g. drill bit, burr, probe, catheter, tube, needle, delivery system).
It is a further object of this invention to provide a system and method to reliably deactivate or disable an instrument being used with a surgical navigation system, after the tool tip has been changed, until the relative location or positioning of the instrument, its attachment, and tool tip is recalibrated or verified.
It is a further object of this invention to provide a system and method with a stable geometry of an emitter and instrument attachments of varying configurations to provide an accurate indication of the location of the attachment""s location relative to a known point or points in the navigation system, for numerous alternative shapes of the instrument attachment.
It is a further object of this invention to provide a system or method with a variable or rotatable geometry between emitter and instrument attachments of varying configurations to provide an accurate indication of the location of the attachment""s location and tip end relative to a known point or points in the navigation system, for varying shapes or orientations of the instrument attachment.
It is a further object of this invention to provide a system or method for positively locking the instrument attachment to the instrument to reduce loosening during a procedure.
It is another object of this invention to provide a system and method for positively generating a display of the position of an instrument attachment or tool tip.
It is a further object of this invention to provide an apparatus and method for bi-directional communication between the surgical navigation system and the instrument attachment to allow control of the instrument, instrument attachment or tool tip by the surgical navigation system or to indicate to the user that the attachment has been properly installed and its position calibrated and is otherwise ready for use in the procedure in concert with the remainder of the surgical navigation system.
Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention in its various embodiments will be realized and attained by means of the elements and combinations particularly pointed out in this description.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention.